Dimethylformamide → HCID 18609891, compound

Participants

Reaction Steps

In the next step of the process, N,S-ditrityl-cysteine is converted to its corresponding activated ester, preferably the 1-benzotriazolyl ester, by reacting N,S-ditrityl-cysteine with 1.0 to 1.3 molar equivalents of 1-hydroxybenzotriazole and dicyclohexylcarbodiimide in an inert organic solvent, i.e. dimethylformamide, at -10° to 10° C for 1 to 3 hours and at 20° to 30° C for an additional hour. The latter mixture containing N,S-ditrityl-cysteine 1-benzotriazolyl ester is cooled to -10° to 5° C and a solution of an equimolar amount of H--Pro--Lys(Boc)--Gly--NH2 and a sufficient amount of an organic acceptor, preferably N-ethylmorpholine, in an inert organic solvent, i.e. dimethylformamide, is added. The mixture is stirred at 20° to 30° C for 20 to 30 hours to obtain N,S-ditrityl-cysteinyl-prolyl-)Nε -t-butoxycarbonyl)lysyl-glycinamide (Trt--Cys(Trt)--Pro--Lys(Boc)--Gly--NH2), tetrapeptide fragment 9-12.

Provenance & Evidence